In an attempt to determine the actual relevance of Pseudomonas aeruginosa as a target of empiric antimicrobial first-line therapy in febrile cancer patients, 44 reports of clinical trials on antimicrobial treatment regimens and 53 reports on the epidemiology of microbiologically documented infections in cancer patients were reviewed. The incidence of infections due to Pseudomonas aeruginosa was 1-2.5% among all patients presenting with first fever during neutropenia, and 5-12% among patients with microbiologically documented infections. The proportion of Pseudomonas aeruginosa infections among cases of gram-negative bacteremia has not generally declined during the past 2 decades. There were marked local and regional differences regarding the incidence of documented Pseudomonas aeruginosa infections. No clear differences between neutropenic and non-neutropenic cancer patients, between patients with solid tumors and those with hematologic malignancies, or between inpatients and outpatients presenting with fever and neutropenia were detected with respect to the likelihood of Pseudomonas aeruginosa involvement. The mortality rate in patients with Pseudomonas aeruginosa bacteremia, particularly with polymicrobial bacteremia or bacteremic pneumonia with Pseudomonas aeruginosa involvement, is considerably high. The beneficial impact on mortality of an empiric antimicrobial treatment regimen with high antipseudomonal activity has not yet been demonstrated unequivocally. Additional factors such as the quality of intensive care management, effective second-line antimicrobial regimens, local resistance patterns, and patient-related cofactors are very likely to influence the outcome of Pseudomonas aeruginosa infections in cancer patients.